This invention relates to cleaning formulation containing a chemical substance which has broad application as a solvent. Such solvent has a set of chemical and physical properties such that it has broad application and can replace many other substances that are detrimental to the environment and have relatively high toxicity to humans. The properties of the invention allow for its application in many cleaning formulations as well as application in the neat state.
Solvents make up a very broad and important segment of the chemical industry worldwide. They have application in all levels of activity from manufacturing of other chemical substances to application in formulated products used in such areas as cleaners, polishes, pesticides, dying, paper manufacturing, coatings, inks etc.
The solvents themselves are as diverse as their applications and uses. The general term "solvent" implies an organic chemical substance i.e. composed of carbon and hydrogen. When only carbon and hydrogen are present, the compounds are classified as hydrocarbons--hence the term "hydrocarbon solvent" refers to solvents of this molecular composition. The primary source of this class of solvents is petroleum. Common petroleum hydrocarbon solvents are mineral spirits, kerosene, Stoddard solvent, various thinners, petroleum distillates, naphtha and aromatics. Most of the hydrocarbon solvents derived from petroleum are mixtures and have variable compositions depending upon the source of the petroleum and the manufacturing parameters employed in their production. Because of their variable composition they also have variable properties which may cause problems in their use applications.
If other elements are introduced into the chemical molecules, new classes of solvents result. The most important elements are chlorine and fluorine (called halogens) and oxygen. Other elements that are less frequently present include nitrogen, sulfur and phosphorus.
Halogenated hydrocarbon solvents contain carbon, hydrogen and chlorine, fluorine or both chlorine and fluorine. As a group these Halogenated solvents have many very desirable properties such as high solvency, high evaporation rates and high flash points. However, because of their detrimental effects on the environment and relatively high human toxicity, most of these substances are either banned from general use or are restricted in their use as solvents.
Oxygenated solvents--those containing oxygen, carbon and hydrogen are further divided into chemical classes such as alcohols, ketones, esters and ethers. Each of these classes has specific properties which leads to it being more specialized in their application as solvents. Certain of these compounds exhibit varying degrees of relatively high human toxicity.
The important properties of solvents include:
the ability to dissolve other materials (solvency). purity and/or consistent composition PA1 evaporation characteristics (vapor pressure and non-volatile residue) PA1 adverse effects on humans (toxicity) PA1 adverse effects on the environment (biodegradation, ozone depletion) PA1 fire hazards (flash point) PA1 availability PA1 cost PA1 regulatory concerns e.g. EPA, OSHA and DOT.
There is no one, perfect solvent that possesses all desirable properties and further many of their properties are related to each other. Therefore compromise is necessary.
Primarily because of regulatory concerns a research effort was initiated to design a chemical molecule that would have the best balance of desirable properties and have the broadest application as a solvent. The primary properties used as a basis were low human toxicity, low environmental impact, low fire hazard and high solvency or broad acceptable solvency.
The first consideration was to select a class of chemical substances for examination that could result in a unique, new, never used substance. Many halogenated molecules were not acceptable due to their environmental and toxicity profiles. Others are extremely costly to manufacture. Oxygenated compounds were discounted as they are more restricted in their applications as solvents. Interest then turned to hydrocarbons. Hydrocarbons are further divided into aliphatic (paraffinic) and aromatic (benzene based). Aliphatic hydrocarbons are found in crude petroleum and are therefore the components of "petroleum distillates. Aromatic compounds are based on the presence of the benzene ring in the molecules and are also found in some crude petroleum. They, however, may also be made synthetically. These compounds are referred to as alkyl benzenes in that they have an alkyl group attached to a benzene ring. They are represented by: ##STR1##
The alkyl group may have any number of carbon atoms indicated by the value of "n" with a practical upper limit of about 20 to 24.
The molecules made in the past were not used in solvent applications and the focus was for intermediates used in the production of detergents and pharmaceuticals.
Alkylation of aromatics is a well studied and industrially utilized reaction. For the alkylation reaction to occur Lewis and Bronsted acids, including a variety of fixed bed catalytic Zeolite systems have been used. The processes for alkylation with Friedel-Crafts type catalysts such as aluminum chloride, boron trifluoride, sulfuric acid, hydrochloric acid and phosphoric acid are well known and used commercially. These systems are very often difficult to handle due to separation and corrosion problems as well as dealing with the effluent streams. Several fixed bed systems based on Zeolites and pillared clays are also described in the literature. This invention is not about a new process, as existing processes can be utilized. It is an invention based on a class of molecules designed for specific applications, in which the molecules have never been made before or utilized as solvents.
In U.S. Pat. No. 3,585,253 inventor S.K. Huang describes a method for the dehydrogenation of paraffins to olefins and subsequent alkylation of specifically benzene using anhydrous HF as the catalyst. The ratio of benzene to olefin in this patent is 6:1 and the HF to olefin is 18:1 at a reaction temperature of 50.degree. C. and atmospheric pressure. Several other patents such as U.S. Pat. Nos. 3,494970, 3,830,865 and 3,494,971 describe similar HF systems.
Usually the current commercial applications of HF catalysts are for the production of linear alkyl benzene (LAB) which is used for the production of detergent linear alkyl benzene sulfonate (LAS). The end use is therefore a detergent.
Other typical systems utilized commercially are the aluminum chloride systems as described in U.S. Pat. Nos. 3,703,559, 3,631,123 and 3,674,885. Because of the problems of corrosion and separation of the products from the catalysts and effluent problems, the focus has shifted towards the cleaner, solid phase systems.
U.S. Pat. No. 3,251,897 describes the alkylation process in Zeolites (crystalline alumina silicates) such as Zeolite X, Zeolite Y, faujasite, heulandite, clinoptilite, mordenite, and dachiardite. Other patents using similar systems include U.S. Pat. Nos. 3,631,120, 3,641,177 and 2,904,607. In particular U.S. Pat. No. 5,043,501 describes the catalytic alkylation and dehydrocyclization using a Zeolite catalyst. In this patent a process is described for the production of 2,6-dimethylnaphtalene by the alkylation of toluene with pentene-1 using a Zeolite with a Constraint Index of not greater than 5, preferably not greater than 3. The method by which Constraint Index is determined is described in U.S. Pat. No. 4,016,218. Specific examples of the catalysts used are ZSM-4, ZSM 12, ZSM-20, ZSM- 50, MCM-22, TEA Mordenite, Clinoptilolite, REY amorphous Silica-alumina, dealuminized Y and Zeolite Beta. The preferred system is based on the MCM-22 catalyst. The catalyst was stabilized by steaming 75 to 100% steam at 315 to 500.degree. C. and pressures of 100 to 2500 Kpa for 1 to 200 hours. Alkylation takes place by flowing the reactants pentene-1 and toluene at a temperature of 50 to 500.degree. F. and pressures of 1 to 25 bar. The toluene to pentene-1 feed ratio expressed as the molar ratio is varied from 0.5:1 to 5:1. The feed weight hourly space velocity (WHSV) of about 0.5 to 100 hr.sup.-1. The space velocity is determined by using the full catalyst weight. The main product produced via batch or continuous mode is the isoamyl toluene (90%).
In U.S. Pat. No. 5,146,026 the alkylation of aromatic hydrocarbons in particular benzene, with C2 to C20 preferably C8 to C16 mono-olefins is described using an aluminum-magnesium silicate catalyst, to give specifically linear alkyl benzene. The reaction temperature is from 150 to 300.degree. C. at a pressure of 10 to 50 kg/cm.sup.2 and the liquid hourly space velocity of 0.5 to 10 hr.sup.-1. A selectivity of up to 95% for linear alkyl benzene. The molar ratio of benzene to aromatic is preferably from 20:1 to 1:1. The most important characteristic of the catalyst which determines the activity, is the surface acidity. The surface acidity can however not be too high as this may cause several side reactions such as oligomerization, isomerization etc. To achieve a high degree of linearity the major part of the surface area of the catalyst must come from pores with a diameter smaller than 50 Angstrom. This prevents the formation of oligomer. 10 to 25% of the pores must be larger than 50 Angstrom. This is obtained by using materials with high porosity, such as silica, alumina, diatomaceous earth etc. and adding these to the catalyst which is preferably synthetic faujasites (Zeolite X or Y).